1. Field of the Invention
This invention relates to information signal reproducing apparatus for reproducing an information signal including audio data recorded in a recorded medium including various kinds of optical discs, for example.
2. Description of the Related Art
An optical disc for music called “CD-DA” (Compact Disc Digital Audio) has been used widely as a recorded medium serving audio data such as music. Audio data encoded in, for example, the LPCM (Linear Pulse Code Modulation) format with which the original sound can be reproduced with relatively high fidelity is recorded in a CD-DA, and it is distributed to an end user. In addition, in late years, a CD-DA in which audio data is recorded by a data storage format called DTS (Digital Theater Systems) has also become available.
This DTS format is an audio reproducing format for forming a sound field with realism using, for example, six speakers called 5.1-channel, which includes five satellite speakers including two front speakers, positioned right and left in front of a listener; a center speaker at the center in front of the listener; two rear speakers, positioned right and left behind the listener, and one sub woofer.
A home audio system supporting the DTS format, which comprises a CD player and speakers capable of reproducing audio data recorded in this DTS format has also become available. It is noted that the “DTS” is a registered trademark of Digital Theater Systems Inc., USA.
In addition, as a recorded medium which provides, for example, digital contents of movies which contain video data of comparatively long time together with audio data such as music, an optical disc called “DVD” (Digital Video Disc/Digital Versatile Disc) has been in practical use.
It is possible to record music information on this DVD. A DVD in which audio data such as music encoded in the LPCM format, for example, with which the original sound can be reproduced with relatively high fidelity as in the above-described case of CD-DA, is recorded is called “DVD-Audio”. On the other hand, a DVD in which video data of relatively long time, such as a movie is recorded together with audio data is called “DVD-Video”.
In a case of DVD-Video, the video data is compressed in an MPEG (Motion Picture Expert Group) format to be recorded. In addition, with regard to audio data such as music, an effect sound, conversation is recorded after data compression in the AC-3 (Audio Coding algorithm-3rd generation) format or in the above-mentioned DTS format in order to form a reproduced sound field with realism.
However, for example, there are some cases that inconvenience occurs when 2-channel stereo audio data (2-channel stereo source) encoded in the LPCM format and recorded in a CD-DA is reproduced using a home audio system supporting the DTS format.
For example, there is a case that a bass range of the reproduced sound is emphasized too much and there is brought an uncomfortable feeling when the audio data of the 2-channel stereo source is divided into the above-mentioned 5.1-channel channel including five satellite speakers and a sub woofer, using the home audio system supporting the DTS format, as in the above-described case. In this case, a user adjusts an equalizer of the home audio system. However, it is troublesome to get a good reproduced sound quality.
In addition, there is a case where some noise is caused, when the 2-channel stereo source audio data is reproduced by using only two front speakers positioned right and left in front of the listener, among the above-mentioned six speakers of 5.1 channel, by a center speaker, two rear speakers and a sub woofer to which no audio data is supplied and a good reproduced sound field cannot obtained when the audio data of the 2-channel stereo source audio data is reproduced using the home audio system supporting the DTS format, as in the above-described case. In such a case, it is required to adjust the volume level of the speakers not in use and the user may feel it troublesome.
This may possibly occur in a home AV (audio visual) system including a DVD player supporting the DTS format. In other words, in a case of a DVD in which audio data is recorded in a format other than the DTS format, there are some cases that a good reproduced sound field cannot be formed in a home AV system supporting the DTS format.
In addition, a CD and a DVD are both an optical disc and reproducing mechanism on a player thereof and a communication path for a reproducing signal can be commonly used. Accordingly, it is possible to form a so-called multi-mode disc player which is capable of reproducing both information signals recorded in a CD and information signals recorded in a DVD.
However, there is a difference in productive intention between the music information recorded in a CD-DA and the audio data recorded in a DVD-Video. Accordingly, in the case of reproducing audio data using the multi-mode disc player, it is necessary to adjust sound level between the cases of reproducing audio data recorded in the CD-DA and the DVD-Video.
In other words, although music information for listening (for appreciation) is mainly recorded in the CD-DA, an average level of audio data is adjusted to be relatively high to be recorded in the CD-DA in order to satisfactorily reproduce the audio data. On the other hand, there are many cases that contents comprised of video data and audio data of movies or the like are recorded in a DVD-Video. The audio data in this case is audio data incidental to video data, and such audio data is often made as an effective sound, and, an average sound level thereof is set relatively low.
Accordingly, it is necessary for the user to raise the sound levels when the user reproduces and watches the audio data and video data recorded in the DVD-Video after reproducing and listening to the audio data recorded in the CD-DA using the multi-mode disc player.
Conversely, it is necessary for the user to lower the sound levels when the user reproduces and listens to the audio data and recorded in the CD-DA after reproducing and watching the audio data and video data recorded in the DVD-Video using the multi-mode disc player because the audios level set for reproducing the DVD-Video is too high for the CD-DA.
In this way, in a case where a CD player, a DVD player, or a multi-mode disc player capable of reproducing both the information recorded in a CD and the information recorded in a DVD, the user should adjust the equalizer, the volume control or the like to form his/her most preferable reproduced sound field in accordance with a signal format of the audio data or a type of a recorded medium in which the audio data to be reproduced in recorded.
Therefore, if the user wants to have a reproduced sound field in accordance with his/her preference, various adjustments with regard to the reproduced sound are required and it takes a lot of time. In addition, there may be a case where the adjustment goes wrong and a finally obtained reproduced sound field is not fit his/her most preferable environment.
In consideration of the above-described problems, it is an object of the present invention to provide an information signal reproducing apparatus capable of forming a most preferable reproduced sound field which fits the user's preference without being influenced by the signal format of the audio data and the recorded medium to be reproduced and without causing inconvenience to the user, and capable of constructing a user-friendly reproducing system.
In order to accomplish the above-described object, the present invention provides an information signal reproducing apparatus which comprises: signal format detection means for detecting signal format information of audio data contained in an input signal; estimating means for estimating a type of the audio data in accordance with the signal format information detected by the signal format detection means; output control means for controlling output of the audio data in accordance with an estimation result output from the estimating means.
According to the information signal reproducing apparatus of the present invention, the signal format information of the audio data to be reproduced is detected through a reproducing signal by the signal format detection means, and it is estimated whether the audio data is a music sound, a movie sound or a speech sound by the estimating means in accordance with the detected signal format information. In accordance with the estimation result output from the estimating means, the audio data to be reproduced is controlled to be appropriately output by the output control means.
In this way, it is not necessary for a user to do various kinds of adjustment for audio data in accordance with the type of the audio data to be reproduced so that it becomes possible to have a preferable reproduced sound field at any time regardless of the type of audio data. That is, a preferable reproducing environment of audio data can be ready at any time without causing a trouble to the user.
In addition, the information signal reproducing apparatus of the present invention further comprises medium type detection means for detecting type information indicating a type of a recorded medium in which the input signal is recorded, wherein the estimating means estimates the type of the audio data in accordance with the signal format information and a detection result output from the medium type detection means.
According to the information signal reproducing apparatus, the type information indicating the type of the recorded medium in which the audio data to be reproduced is recorded is detected by the medium type detection means through the input signal, and the type of the audio data is estimated by the estimating means in consideration of the detected type information. In accordance with the estimation result output from the estimating means, the audio data to be reproduced is appropriately controlled to be output by the output control means.
In addition, the medium type detection means may detect the type of the recorded medium in accordance with recorded medium selection information indicating that a user selects the recorded medium being a source of the input signal.
In this way, it is possible to estimate the type of the audio data to be reproduced in consideration of the type of the recorded medium in which the audio data to be reproduced is recorded as well as the signal format information, and thus, more accurate estimation can be carried out. As a result, it becomes possible to have a preferable reproduced sound field regardless of the type of audio data and without causing a trouble to the user.
In addition, the information signal reproducing apparatus of the present invention is characterized in that the signal format detection means detects a data storage format or an encoding format of the audio data as the signal format information.
According to this information signal reproducing apparatus, the data storage format or the encoding format of the audio data is detected as the signal format information by the signal format detection means. The data storage format and the encoding format include, for example, LPCM, AC-3, DTS, MPEG and the like. In accordance with these data storage format or the encoding format, the type of the audio data to be reproduced is estimated.
It is possible to estimate the type of the audio data to be, a music sound in a case where the encoding format is LPCM, and a movie sound in a case where the encoding format is AC-3, DTS or MPEG, for example, in accordance with a currently-used status of the encoding format or the like. In addition, it is possible to appropriately control the output of the audio data in accordance with an estimation result based on experience.
In addition, the information signal reproducing apparatus of the present invention is characterized in that the signal format detection means detect a reproducing channel number of the audio data as the signal format information.
According to the information signal reproducing apparatus, the reproducing channel number of the audio data is detected as signal format information by the signal format detection means. For example, 1-channel (monaural), 2-channel (stereo), 4-channel, 5.1-channel (multi-channel) and the like are included in the reproducing channel numbers of the audio data. In accordance with the reproducing channel number, a type of the audio data to be reproduced is estimated.
Accordingly, it becomes possible to estimate the type of the audio data in consideration of the currently-used status (in other words, experience so far) of the channel number, for example, in a case of 1-channel, the audio data is a speech sound; in a case of 2-channel or 4-channel, a music sound; and in a case of 5.1-channel, a movie sound. According to a result of such an educated estimation, it becomes possible to control output of the audio data appropriately.
Furthermore, the information signal reproducing apparatus of the present invention is characterized in that the signal format detection means detects a sampling frequency of the audio data as the signal format information.
According to this information signal reproducing apparatus, the sampling frequency of the audio data is detected as the signal format information by the signal format detection means. The sampling frequency of the audio data may be high in a case of a music sound in order to reproduce the original sound faithfully and may be lower than the case of the music sound in a case of a speech sound. In accordance with a detected sampling frequency, the type of the audio data to be reproduced is estimated.
In this way, in consideration of the used status of the conventional sampling frequency (in other word, experience so far), it becomes possible to estimate the type of the audio data. According to a result of such an educated estimation, it becomes possible to control output of the audio data appropriately.
In addition, the information signal reproducing apparatus of the present invention is characterized in that the output control means controls an output level of the audio data.
According to this information signal reproducing apparatus, it becomes possible to control output levels of the audio data appropriately in accordance with the type of the audio data. For example, in a case where the estimation result with regard to the type of the audio data output from the estimating means is a music sound, the output level of a sound of the audio data is attenuated, and in a case where the estimation result is a movie sound, the output level of a sound of the audio data is raised. It is preferable that the output volume levels of various audio data are substantially the same regardless of the type of the audio data in consequence.
Furthermore, the information signal reproducing apparatus of the present invention is characterized in that the output control means controls a frequency characteristic of a sound of the audio data.
According to this information signal reproducing apparatus, in a case where an estimation result indicating the type of the audio data output from the estimating means is a movie sound, high audio frequencies of the audio data are controlled; in a case where the estimation result is a music sound, low audio frequencies of the audio data are attenuated; and in a case where the estimation result is a speech sound, voice band components are emphasized. Accordingly, a preferable reproduced sound field can be obtained at any time.
In addition, the information signal reproducing apparatus of the present invention is characterized in that the output control means controls a selection of an output channel of a sound of the audio data.
According to this information signal reproducing apparatus, a sound from an unused channel is muted in accordance with the estimation result indicating the type of the audio data output from the estimating means. In this way, a preferable reproduced sound field can be obtained in accordance with the type of the audio data.
In addition, an information signal reproducing apparatus of another aspect of the present invention includes: channel number detection means for detecting information indicating a reproducing channel number of audio data contained in an input signal; and power source control means for controlling a power supply for an audio data amplifying circuit provided corresponding to each reproducing channel in accordance with the information indicating the reproducing channel number detected by the channel number detection means.
According to this information signal reproducing apparatus, the reproducing channel number of the audio data to be reproduced is detected by the information detection means, and the power is supplied to only a speaker amplifier (power amplifier) corresponding to a speaker in actual use in accordance with the number of reproducing channels. In addition, muting means may be further included so that an unused speaker is disabled so as not to output sound.
In this way, it becomes possible to prevent noise from being emitted from a speaker to which no audio data is supplied and to set a preferable reproducing environment for the audio data without deteriorating the S/N ratio of the reproduced sound field.
In addition, an information signal reproducing apparatus of another aspect of the present invention includes detection means for determining whether or not an input signal contains video data, and a power source control means for receiving the video data and controlling power supply to a video display device which displays a video corresponding to the video data, in accordance with a detection result output from the detection means.
According to the information signal reproducing apparatus, the input signal is detected whether or not it includes video data by the information detection means. In a case where the input signal contains video data, an instruction to apply power is transmitted to a video display device, and in a case where the input signal contains no video data but only audio data, an instruction to cut off the power is transmitted to the video display device. Of course, in a case where the information signal reproducing apparatus of the present invention includes circuits for outputting and displaying the video data, the power supply to such video output circuit and video display circuit may be controlled.
Therefore, in accordance with the existence of the video data, the power supply to the video display device can be controlled. Accordingly, it becomes possible to have a most preferable reproducing environment for audio data and video data without causing any trouble to the user.